The News of the World confirmed in a statement today that Edmondson, who was hired by former editor Andy Coulson, had been suspended on full pay. Coulson is now David Cameron's director of communications.

"A serious allegation has been made about the conduct of a member of the News of the World staff," the paper said.

"We have followed our internal procedures and we can confirm that this person was suspended from active duties just before Christmas.

The paper added that it is carrying out its own internal investigation into the allegation and that "appropriate action will be taken" if they are found to be true.

"The News of the World has a zero-tolerance approach to any wrongdoing," it said.

A spokeswoman for News of the World publisher News International declined to comment further on the nature of the allegation against Edmondson or the internal investigation.

However, MediaGuardian.co.uk understands that it relates to an incident or incidents that took place in 2005.

The News of the World and Coulson have always claimed that the only journalist involved in phone hacking was Clive Goodman, the former royal correspondent who was jailed with Mulcaire in January 2007.

Miller is suing News Group, the News International subsidiary that publishes the News of the World, and Mulcaire, accusing them of breaching her privacy and of harassing her "solely for the commercial purpose of profiting from obtaining private information about her and to satisfy the prurient curiosity of members of the public regarding the private life of a well-known individual".

In a 20-page document lodged with the high court, Miller's solicitor, Mark Thomson, and barrister, Hugh Tomlinson, cite extracts from paperwork and other records that were seized by police from Mulcaire in August 2006. The material has now been released to the lawyers on the orders of a high court judge.

The document claims Mulcaire's handwritten notes imply that Edmondson instructed him to intercept Miller's voicemail and that the operation also involved targeting her mother, her publicist and one of her closest friends as well as Jude Law, her former partner, and his personal assistant. During the operation Mulcaire obtained confidential data held by mobile phone companies in relation to nine different phone numbers, the notes reveal.

The document, which was released to the Guardian by the high court, suggests that the hacking of the two actors' phones was part of a wider scheme, hatched early in 2005, when Mulcaire agreed to use "electronic intelligence and eavesdropping" to supply the paper with daily transcripts of the messages of a list of named targets from the worlds of politics, royalty and entertainment.

It also records that at the 2007 trial of Goodman it was revealed that Mulcaire wrote the word "Clive" in the top left-hand corner of his notes of hacking undertaken on Goodman's behalf. According to the high court document Mulcaire's notes for the hacking of Miller "in several cases were marked 'Ian' in the top left-hand corner, which the claimant infers to be Ian Edmondson".

Edmondson was also named late last year in a separate phone-hacking case brought by Nicola Phillips, former assistant to the PR agent Max Clifford. The judge in that case has ordered Mulcaire to say if it was Edmondson who instructed him to intercept her voicemail in the spring of 2006. Mulcaire has appealed against the order.

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